In the manufacture of cigarette articles, tobacco is dispensed onto a moving belt or web, where it is shaped into a continuous rod. As the rod moves along the cigarette making apparatus, its brought into contact with a continuous length of cigarette paper, moving at the same speed. Various guides on the machinery fold one edge of the paper to wrap it around the tobacco rod, but leave the opposite edge, or "lap" standing upright so as to be exposed. At this point, glue is applied to the inside surface of the exposed edge portion, and thereafter machine guides fold the exposed edge portion so as to overlap the opposite edge of the paper, the glue thus adhering the opposite edges of the paper together.
Traditionally, the preferred glue for cigarette applications is starch paste. For starch paste to effectively seal the ends of the cigarette paper, however, it is necessary to apply the paste in a uniform, thin layer of a controlled amount.
At one time in the industry, paste was applied to the paper by dispensing it through a nozzle using pressure to control the volume. This worked for relatively slow speed machinery. But, as cigarette making machines became faster, machinery manufacturers replaced nozzle applicator systems with a paste wheel system, such as disclosed in U.S. Pat. No. 3,105,498, in order to improve the application of the paste on faster machines.
Conventional starch paste applicators, such as the Molins Mark IX starch paster, continue to use a paste wheel applicator. In the Molins apparatus, starch paste is supplied from a starch pot, which includes a moveable piston plate closing one end. A hydraulic ram, acting on the piston plate, forces paste from the starch pot, through a connecting line, to a paster nozzle. The nozzle is spring loaded against a concave wheel so as to apply a film of starch. The concave wheel, in turn, is in contact with the paste wheel so as to transfer paste to the paste wheel. Finally, the paste wheel contacts the cigarette paper lap so as to transfer paste to the cigarette paper.
The use of the double paste wheel transfer is intended to ensure that a uniform, controlled amount of paste is applied at the correct position to the paper lap. However, in order to function properly, the paste wheel system components must be adjusted to very close tolerances. Thus, the spring pressure on the nozzle must be adjusted to suit the consistency of the starch in use. The height of the paste wheel relative to the concave wheel must be set to ensure that the correct transfer of starch is achieved. The paste wheel periphery and concave surface of the concave wheel must be set parallel to and in contact with each other. Also, the paster position must be adjusted to apply the starch correctly onto the cigarette lap. In practice, the need for close adjustment tolerances causes a considerable amount of defective product ("pop opens") and down time of the cigarette making machinery. Also, the paste wheel systems include several high wear items. These items are expensive to replace, due to the precision required in machining the parts.
As cigarette making equipment improves, it would be desirable to operate at still higher speeds. However, the known starch paste applicator systems have proven inadequate for higher speed operations.
Because of the high incidence of defective products, or in order to speed up the manufacturing line, some manufacturers have switched from starch paste to a PVC-type of sealant. It would be desirable, however, to have a system capable of applying starch paste with better consistency, which is easier to adjust and operate, and which can function efficiently at higher speeds. It would also be desirable to reduce maintenance costs relative to the paste wheel systems.